Blood is made up of four components:
 

• Red blood cells, which carry oxygen around the body.
• White blood cells, which help to prevent and fight infections.
• Platelets, small particles which help the blood to clot.
• Plasma, the liquid part of the blood in which many proteins and other substances are dissolved.

Apheresis is a medical procedure that involves removing whole blood from a patient and separating the blood into individual components so that one particular component can be removed. The remaining blood components then are re-introduced back into the bloodstream of the patient.

Therapeutic apheresis is used for the treatment of certain medical conditions in which a part of the blood that contains disease-provoking elements is removed. Apheresis is also called pheresis or hemapheresis. The procedure is done in a clinic or hospital.

All apheresis procedures involve connecting the blood in the patient’s veins through tubing to a machine that separates the blood into its components. The separation is done by either a centrifuge process or a filtration process in the machine. After the separation, the desired component is removed while the remainder of the components are reinfused back to the patient. This requires one or two needles to be inserted into the veins, usually one in each arm. In some patients with small arm veins it may be necessary to insert a special catheter.

• Therapeutic Plasma Exchange
• Therapeutic Red Blood Cell Exchange
• Therapeutic Cytoreductions
  • Therapeutic Leukapheresis
  • Therapeutic Plateletpheresis
• Peripheral Blood Progenitor Cell (stem cell) harvesting
• Photopheresis
• LDL-Apheresis

The actual time depends on a number of factors including: the procedure being performed, the disease being treated, the size of the patient, the type of machine being used, the vascular access, patient's hemodynamic stability, and patient's hematocrit, blood flow rate and plasma flow rate. Generally, procedures range from one to four (1 - 4) hours.

There is generally no magic number of procedures that should be performed for a given patient. In many cases, the patient is reevaluated after 2 or 3 procedures to see if they are responding. For many diseases, such as the neurologic syndromes, the clinicians have set formulas that they follow. This is fine, as long as it seems reasonable. For example, they may do 5 procedures over two weeks. Other times, the procedure is done daily until the patient improves (examples: TTP patients. Improvement in the patient with TTP is followed by monitoring the platelet count and the LDH level). Some procedures are one-time only -- for example, red cell exchange is done one time in most patients in crisis. However, some patients are on a routine schedule of treatment such as once every 4 weeks to prevent the need for emergent treatment.

Serious complications to therapeutic apheresis are rare. Minor complications can include bleeding at the needle sites and feelings of lightheadedness that usually resolve quickly. More serious complications can occur when apheresis is used to treat serious conditions and include:

• Bleeding or a tendency to bleed because clotting factors are removed
• Infection or a tendency toward infection because the immune system is somewhat suppressed when antibodies are removed
• Low blood pressure as fluids are removed
• Muscle cramping as low blood calcium can occur and other electrolytes can be imbalanced
• Reactions to the replacement fluids occur occasionally. These are more common when fresh frozen plasma is used, but serious reactions are rare.

When used in a therapeutic manner, the apheresis procedure is individualized regarding the frequency of treatments, the volume of blood or components to be removed, and the type of solution used for volume replacement.

The following list of conditions for which therapeutic hemapheresis may be of benefit is not all-inclusive. Therapeutic hemapheresis can be used in the treatment of:

• Myasthenia gravis
• Waldenstrom’s macroglobulinemia
• Goodpasture syndrome
• Familial hypercholesterolemia (LDL apheresis)
• Hyperviscosity syndrome
• Thrombotic thrombocytopenia purpura (TTP)
• Leukostasis caused by leukemia
• Systemic lupus
• Antibody mediated rejection in solid organ transplant
• Graft-versus-host disease (GvHD) of skin and/or liver (photopheresis)

Hemapheresis is generally avoided if a patient has active infection, unstable heart or lung complications or is too unstable to undergo the procedure.

The overall status of the patient as well as the seriousness and progression of the disease in question are all taken into consideration relative to these contraindications for each individual patient.